History
Winterton-on-Sea may not have been a site in the Post Office/BT SHF network. It has been included since it was identified as part of 1960s network plans. A document at the National Archives mentions the following "work expected to be approved by 31st March 1967": Winterton-London Radio Link (960 circuits) The provision of one two-way operational channel and one two-way protection channel between Winterton and Stoke Holy Cross [plus additional channel onwards to London].
The significance of Winterton-on-Sea is as a "landing station" for a number of cables connecting the UK with Denmark, Germany and (later) The Netherlands. The first group entered service in 1964, totalling 360 circuits, and it seems at this stage a coaxial cable (with potential capacity for 960 circuits per "tube") was provided between Norwich and Winterton. It is likely the proposed SHF link was in the expectation of further expansion - in 1971 a new cable between Winterton and Fedderwarden provided 1260 circuits. Unless there were other factors it seems most likely the additional traffic would have been accommodated by using spare capacity in the cable to Norwich though perhaps it was intended to provide a measure of resilience. We understand Winterton was connected to other cable landing sites along the Suffolk coast - complete failure of the cable to Norwich would have led to a significant reduction in capacity but not a total loss of service.
Further cables landed at Winterton in the 1980s and 1990s however a 1974 map of International circuits suggests the SHF link from London terminated at Norwich (Stoke Holy Cross). Between Norwich and Winterton a capacity of 2700 circuits is shown, via cable. This suggests the SHF link from Winterton was never approved - however it's clear a proportion of the traffic over the London to Norwich SHF route was destined for other countries.